To reveal latrine use patterns in low density Japanese badgers, a novel “Trace Recorder” system was developed to track three individuals (two males and a female) between two groups in Hinode-town, a suburb of Tokyo in 1997. A young adult male was observed to intrude into the ranges of neighbouring adult females during the mating season and to make frequent visits to hinter and border latrines within their natal ranges. Findings suggest that extra-group mating may be facilitated by the border latrine communication where scent marking can be effective information sources of badger presence and oestrous status.

To assess the degree of competition for food items between non-natives and natives, dietary overlap among three carnivore species living sympatrically in the area of Isumi City, southeastern Chiba Prefecture, central Japan, was analyzed by examining the gut contents of 221 animals collected from spring through summer 2006. The animals comprised two introduced species, the raccoon Procyon lotor and the masked palm civet Paguma larvata, and a native species, the raccoon dog Nyctereutes procyonoides. All three species were found to eat berries and seeds, amphibians and arthropods. The raccoons ate more crustaceans, the masked palm civets ate more mollusks, and the raccoon dogs ate more human meal scraps than the other two species. The food diversity of raccoons was lowest in both spring and summer. The dietary overlap was highest between raccoon dogs and masked palm civets. The degree of dietary overlap among the three species increased from spring to summer. These results suggest that overlap of food items is high and the degree of food resource segregation is low among the three species.

The armor-like folded skin of the Indian rhinoceros (Rhinoceros unicornis) was examined by CT image analyses and microscopic observation. The three-dimensional reconstructed images demonstrate that the folded skin has the subcutaneous tissues including cutaneous muscles and connective tissues inserted to the deepest holes and grooves of 2–3 mm thickness in each fold. The cutaneous muscles are well-developed in subcutaneous tissues, in which many small blood vessels are found. We conclude that the folded skin acts as a thermoregulator, since the thin blood vessels and capillaries and cutaneous muscles in the subcutaneous tissues transmit the thermal energy from the core region of the body to the skin folds. We suggest that the greater Indian rhinoceros, Rhinoceros unicornis, has evolved the extraordinary thermoregulation mechanism in the folded skin adapted to high temperature in the tropical and subtropical regions.

Members of the Felidae, being found at the top of the trophic hierarchy in an ecosystem, usually require extremely large habitat ranges. Thus, most cat species are found only on continents or large islands. The leopard cat Prionailurus bengalensis, the most widespread species of East Asian cat, is an exception to this rule, occurring on several small islands as well as larger islands and the Asian continent. Using published data for 38 East Asian islands, I evaluated the effects of geographical and biological factors on the persistence of the leopard cat population on an island by using regression analyses. The results suggested that the probability of existence of this cat species on an island increased with increasing species richness of potential prey, or with decreasing species richness of potential competitors. Geographical variation in the feeding habits of the leopard cat was also examined to clarify its ecological adaptation to different environments. The leopard cat chiefly preys on rodents but occasionally also feeds on other kinds of animals depending on region. On small islands with a small number of carnivore species, the cat frequently feeds on non-mammalian prey. This suggests that the cat potentially utilizes a variety of food items. The diet width of the leopard cat may be being determined by availability of prey items and intensity of interspecific competition.

The brachial plexus of the okapi showed the evolutionarily intermediate status between the underived ruminants and the giraffe with elongated neck. Whereas the C6 was the thinnest among the roots of the brachial plexus, the C7, C8 and T1 were much thicker in the okapi. From the data we concluded that the okapi was equipped with the intermediate characteristics of the disappearing C6. Although the nerve of the C6 should be elongated in accordance with the long neck in the Giraffidae, the extraordinary elongation of the C6 may have no advantages in the function of the innervations. In the okapi, therefore, we suggest that the function of the C6 has been mainly replaced with that of C7.

The hyoid apparatus was described in order to examine morphological differences among eight species of carnivores. Confusion in terminology of its proximal elements is corrected at first. The tympanohyal, attached to the petrosal part of the temporal bone, is a small bone inside the stylomastoid foramen in the red fox, raccoon dog (Canidae), Asiatic black bear (Ursidae), and masked palm civet (Viverridae), in contrast, it is not visible in the Japanese weasel, Siberian weasel, Japanese marten (Mustelidae) and raccoon (Procyonidae). Inter-specific structural differences of the remainder of the hyoidean elements are not distinct. The basihyal attaches to the ceratohyal and thyrohyal. The thyrohyal is also connected with the thyroid cartilage. The anterior cornu besides the tympanohyal comprises, from distal, three bones; the ceratohyal, epihyal, and stylohyal, and a band of cartilage. The tympanohyal, if present, is connected to the stylohyal via the tympano-styloid synchondrosis. Allometry between the length of the hyoidean elements and that of the skull shows isometric growth. This reflects simply the masticatory function of the hyoid apparatus. The tympanohyal of the mustelids and procyonid is possibly covered and hidden by the tympanic bulla.